February 2011

 

NEWS & OPINION

 

Optimizing refractive outcomes in presbyopia patients


by Enette Ngoei EyeWorld Contributing Editor

   

Results show SIM-LASIK with the AcuFocus KAMRA inlay to be a promising procedure for presbyopia patients with ametropia

AcuFocus KAMRA inlay

The AcuFocus KAMRA inlay for the treatment of presbyopia Source: Perry S. Binder, M.D.

While the AcuFocus (Irvine, Calif.) KAMRA intracorneal inlay is undergoing clinical trials for FDA approval to treat presbyopia patients, surgeons abroad have already started to combine the inlay implantation surgery with LASIK.

The procedure, called SIM-LASIK, allows surgeons to optimize refractive outcomes by setting post-op refractive targets. Minoru Tomita, M.D., executive director, Shinagawa LASIK Center, Tokyo, whose practice has performed 1,000 SIM-LASIK procedures since June 2009, reported positive results.

The technology

The KAMRA inlay has an overall diameter of 3.8 mm, which is smaller than a contact lens. It has a 1.6 mm center aperture, which is a small opening in the center that creates a pinhole effect. The device is 5 microns thick, made of polyvinylidene fluoride and carbon, and it has 8,400 random holes for oxygen and nutrition flow. The AcuFocus corneal inlay is designed to improve depth of focus, allowing the eye to see near and intermediate objects more clearly, Dr. Tomita said.

Surgical technique

A 200 micron corneal flap is created in the non-dominant eye. Using the Femto LDV (Zeimer Ophthalmic Systems, Port, Switzerland), the flap thickness can be reproduced almost exactly every time, Dr. Tomita said. Excimer laser ablation is then performed and the KAMRA inlay is positioned and centered under the flap using the AcuTarget system, which guides surgeons in the proper placement of the device. The entire procedure usually takes 10 minutes, Dr. Tomita said.

Results

Presenting data on 439 eyes that underwent SIM-LASIK at the Shinagawa LASIK Center, Dr. Tomita said that uncorrected distance visual acuity saw a mean improvement of eight lines from 20/125 pre-op to 20/20 at 6 months post-op. This was a statistically significant difference, Dr. Tomita said. In addition, mean uncorrected near visual acuity improved four lines from J9 pre-op to J2 at 6 months post-op.

Follow-up is currently at 14 months and results have been stable, Dr. Tomita reported.

Although there have not been any complications during surgery, post-op care found that some patients suffered from dry eye, as with regular LASIK patients. However, with dry eye treatment, patients' symptoms improved, Dr. Tomita said.

The surgery is easy for refractive surgeons because it only involves the additional implanting of the inlay after excimer laser ablation and otherwise follows the same technique as regular LASIK, Dr. Tomita said. "It's an easy but effective treatment," he said. Dr. Tomita pointed out that getting good centration of the KAMRA inlay is rather difficult but very important. Therefore, surgeons new to the technique will have a bit of a learning curve before they are able to center the inlay well. The AcuTarget machine developed by AcuFocus to guide surgeons in centration is helpful, Dr. Tomita said.

Dr. Tomita said that the AcuFocus KAMRA's pinhole center is an important part of the procedure's success. "Because its center is a pinhole, there's no risk of causing opacities."

In the 1,000 cases done at Shinagawa LASIK Center, 92% of patients are spectacle independent and very happy, Dr. Tomita said. He concluded that SIM-LASIK is an effective treatment in a high volume practice, and patients have shown improvements in both near and distance visual acuity.

Outside of Japan, the simultaneous bilateral LASIK and unilateral KAMRA inlay implantation technique has shown equal promise. At the XXVII European Society of Cataract and Refractive Surgeons meeting in Barcelona, Donald T.H. Tan, F.R.C.Ophth., director, Singapore National Eye Center, Singapore, reported initial results of patients who underwent the procedure. One week post-op, patients had a visual acuity near J3 and improved to J2 by 1 month, he said. Although long-term data is needed, Dr. Tan said early reports indicate highly satisfied patients, and the lens shows promise of becoming the best means of presbyopia correction currently available. When used in combination with refractive surgery, Dr. Tan said the standard contraindications of keratoconus or dry eye remain.

Editors' note: Dr. Tomita has no financial interests related to his comments.

Contact information

Dr. TomitaTomita: +81.3.5221.2207, tomita@ shinagawa.com

Related articles:

Presbyopia case management by Erin L. Boyle EyeWorld Senior Staff Writer

A scleral approach to presbyopia by Vanessa Caceres EyeWorld Contributing Writer

Monovision revisited by Erin L. Boyle EyeWorld Senior Staff Writer

Presbyopia: How to treat the near emmetrope by Michelle Dalton EyeWorld Contributing Editor

Corneal approaches to presbyopia: Creating multifocal corneas by Enette Ngoei EyeWorld Contributing Editor

The pioneer spirit: Unmapped presbyopia correction territories by Maxine Lipner Senior EyeWorld Contributing Editor

Presbyopia: Optimizing refractive outcomes in patients Presbyopia: Optimizing refractive outcomes in patients
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